“It’s unfortunate because he’s always been one of our better Ds,” said Bruins coach Claude Julien. “He always seems to step his game up at playoff time. That part, you’re definitely going to miss. It’s part of the game that’s there.

“You have to understand those things are going to happen every once in a while. Right now, we still feel we have enough good players that they’re going to step in at his spot and fill it as best as they can.”

Seidenberg was hurt Friday when he tangled with Ottawa’s Cory Conacher behind the Boston net in the third period of the Bruins’ 5-0 win. Seidenberg needed help returning to the dressing room.

He did not travel to Ottawa for Saturday’s rematch.

Seidenberg, 32, ends his season with one goal and nine assists in 34 games. Seidenberg was averaging 21:50 of ice time per game, second after Zdeno Chara.

This is the second time Seidenberg has had a season cut short because of injury. On April 3, 2010, Seidenberg suffered a torn tendon in his left arm. He missed the remainder of the regular season and the playoffs.

It is a loss the Bruins will feel deeply. Seidenberg is a rugged, shift-munching stay-at-homer. The left-shot Seidenberg is just as comfortable on the right side.

Seidenberg’s game improves in the playoffs. He logged 25:59 of ice time per game during last year’s Stanley Cup run. In 2010-11, Seidenberg averaged 27:37 of action. For most of the last three postseasons, the Bruins united Chara and Seidenberg as their shutdown duo.

Chara will be without his usual playoff partner. Chara, already averaging 25:02 of ice time, will have to assume more defensive responsibilities. Before the season, the Bruins had hoped to reduce Chara’s regular-season workload. Chara played 24:56 per game last year.

Seidenberg had been skating on the second pairing. While Chara drew top forwards, the coaching staff tasked Seidenberg with shutting down opposing second lines. Seidenberg was also a regular on the penalty kill, where he averaged 2:24 of action.

Seidenberg was in the last season of his four-year, $13 million contract; his four-year, $16 million extension kicks in next season.

“We’re not going to replace him,” said rookie defenseman Torey Krug. “He’s an unbelievable player for us. He plays such a big role on this team. He’s part of the heart of this team. There’s a reason we brought him back for the length of his contract.

“Now we’ve just got to do it by committee. There’s got to be guys that pick up the slack here and there. It’s not just going to be one guy. It’s going to be a group effort. It starts from Z all the way down to who we bring up from Providence.”

Saturday’s 4-3 loss marked the first game without Seidenberg. Matt Bartkowski, elevated to top-pairing status because of the absences of Seidenberg and Chara (undisclosed injury, day to day), played a game-high 22:57. Bartkowski had three shots, five hits, and two blocked shots.

Soderberg concussed

Carl Soderberg didn’t make the trip because of concussion-like symptoms. He was injured when he was checked into the glass in the third period Friday.

“He got dinged up on that hit,” said coach Claude Julien. “He had some symptoms. We don’t know how serious, but serious enough that we left him behind to make sure he’s being evaluated.”

Soderberg missed the first six games of the season because of a sprained ankle. Soderberg, the No. 3 left wing, has five goals and 14 assists in 32 games while averaging 13:37 per appearance
.

Nick Johnson was brought up on an emergency basis. Johnson was the No. 3 right wing. Matt Fraser, who had been the third-line right wing, switched to fill Soderberg’s spot on the left side.

Second time around

Ryan Spooner, a native of nearby Kanata, made his second NHL appearance in his hometown. On March 21, in his first game in Ottawa, Spooner played just 8:17 with one shot in a 2-1 Bruins win. It was his third career NHL game. “I’ve been making plays that I’m capable of,” Spooner said. “I was kind of nervous out there. I had the puck on my stick and was trying to get rid of it. Now I feel like the play’s kind of slowed down a little bit. I’m a little bit more comfortable. I think the last 5-6 games, I’ve played a lot better.” Spooner had one shot in 11:25
of ice time . . . Jordan Caron challenged Ottawa tough guy Matt Kassian to a fight. Caron didn’t like Kassian’s heavy hit on David Warsofsky in the first period. Caron ceded 36 pounds to Kassian, but held his own against the heavyweight . . . Niklas Svedberg, projected to be Tuukka Rask’s backup Saturday, watched the game from the press box instead. Svedberg had to be assigned for the Bruins to be under the 23-player roster maximum . . . With Chara out, Gregory Campbell was the third alternate captain.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.

Thanks & Welcome to Globe.com

You now have unlimited access for the next two weeks.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.